DESCRIPTION: The long term goal of this application is to understand better how the retina processes visual information. During this grant period whole- cell and single-channel voltage-clamp techniques, calcium imaging and electro- physiological recordings will be used to study the function of particular neurons and how their function is controlled and modulated. The studies will be carried out on isolated cells in culture and retinal slices from the white bass and turtle. Specifically the studies will: 1) learn how the neuromodulator dopamine regulates calcium influx into white bass horizontal cells and study the impact of this regulation on the cells' response properties; 2) characterize the calcium current of white bass bipolar cells and learn if dopamine or GABA can modulate calcium entry into these cells, and learn the effect any modulation might have on the cell's response properties and subsequently synaptic transmission; and 3) characterize the different GABA receptors found on turtle retinal ganglion cells and study their role in ganglion cell response formation. These studies are important because they will lead us to a better understanding how retinal neurons, and neurons in general, function. Also, to understand and treat retinal disease, an understanding of healthy retinal function is necessary.